From ab55da589c27e65e54956b32a1550e21169447ae Mon Sep 17 00:00:00 2001
From: Diego Martinez <kaeza@users.sf.net>
Date: Thu, 18 Dec 2014 23:50:31 -0300
Subject: [PATCH] Faster string.split implementation.
---
builtin/common/misc_helpers.lua | 44 ++++++++++++++++-----------------
1 file changed, 22 insertions(+), 22 deletions(-)
diff --git a/builtin/common/misc_helpers.lua b/builtin/common/misc_helpers.lua
index 713555109..2ee990e5c 100644
--- a/builtin/common/misc_helpers.lua
+++ b/builtin/common/misc_helpers.lua
@@ -155,33 +155,33 @@ function dump(o, indent, nested, level)
end
--------------------------------------------------------------------------------
-function string.split(str, delim, include_empty, max_splits)
+-- Localize functions to avoid table lookups (better performance).
+local table_insert = table.insert
+local str_sub, str_find = string.sub, string.find
+function string.split(str, delim, include_empty, max_splits, sep_is_pattern)
delim = delim or ","
- max_splits = max_splits or 0
- local fields = {}
- local num_splits = 0
- local last_pos = 0
- for part, pos in str:gmatch("(.-)[" .. delim .. "]()") do
- last_pos = pos
- if include_empty or part ~= "" then
- num_splits = num_splits + 1
- fields[num_splits] = part
- if max_splits > 0 and num_splits + 1 >= max_splits then
- break
- end
+ max_splits = max_splits or -1
+ local items = {}
+ local pos, len, seplen = 1, #str, #delim
+ local plain = not sep_is_pattern
+ max_splits = max_splits + 1
+ repeat
+ local np, npe = str_find(str, delim, pos, plain)
+ np, npe = (np or (len+1)), (npe or (len+1))
+ if (not np) or (max_splits == 1) then
+ np = len + 1
+ npe = np
end
- end
- -- Handle the last field
- if max_splits <= 0 or num_splits <= max_splits then
- local last_part = str:sub(last_pos)
- if include_empty or last_part ~= "" then
- fields[num_splits + 1] = last_part
+ local s = str_sub(str, pos, np - 1)
+ if include_empty or (s ~= "") then
+ max_splits = max_splits - 1
+ table_insert(items, s)
end
- end
- return fields
+ pos = npe + 1
+ until (max_splits == 0) or (pos > len)
+ return items
end
-
--------------------------------------------------------------------------------
function file_exists(filename)
local f = io.open(filename, "r")
--
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